1. Field of the Invention
This invention relates to a part gripping hand apparatus for gripping parts handled in the work assembling operation.
2. Related Background Art
Heretofore, hand apparatuses for gripping parts assembled in the parts assembling work have been prepared in advance for exclusive use for these parts in conformity with the shapes of the respective parts and setting has been done so as to change the hand apparatus each time the parts to be gripped are changed.
For example, where the parts are of a round shape, there has heretofore been available a collet chuck which can grip almost all rounded parts irrespective of their sizes as long as the shapes thereof are round. On the other hand, there is known a hand apparatus having two finger members and gripping a part by nipping the part from the opposite sides thereof by these finger members.
However, hand apparatuses of conventional construction are constructed as hand apparatuses for exclusive use for respective shapes and therefore can grip parts irrespective of their sizes if the shapes of the parts are those to which the hand apparatuses are directed, but cannot grip parts well if the shapes of the parts are not those to which the hand apparatuses are directed, and this leads to the necessity of preparing various hand apparatuses, which in turn leads to problems in terms of both cost and space.
There are Japanese Laid-open Patent Application No. 57-1686 and Japanese Laid-open Utility Model Application No. 60-74986 as the prior art with respect to the present invention, particularly, an apparatus provided with three fingers and gripping an article by the three fingers being driven by a drive shaft.
Also, there is Japanese Laid-open Patent Application No. 61-33883 (U.S. Pat. No. 4,598,942) as a gripping apparatus of a robot for automatically gripping an article or a work piece which comprises a motor rotatable selectively in one direction and the opposite direction and having a shaft working as an output drive member, a plurality of gripper assemblies capable of being driven by said output drive member, each of said gripper assemblies having gripper finger means protruding laterally from the distal end of a rotatable shaft having a lever fixed to the shaft and protruding laterally from the shaft, connecting means disposed between the shaft of each said gripper assembly and said output drive member, and means for controlling said connecting means to limit the torque transmitted from said output member to the shaft of each said gripper assembly through said connecting means to a relatively low value until at least all said gripper fingers contact said article, and change said torque to a relatively high torque of a magnitude suitable for handling said article without causing slippage after said gripper fingers have contacted said article.